Background Hamstring muscle strain injuries are a prevalent non-contact injury incurred by field sport athletes. A low level of hamstring muscle strength has been reported to be a risk factor for hamstring muscle strain injury, whereby reliable, clinically-oriented assessments of hamstring muscle strength are required to assist clinicians to implement ‘targeted’ injury prevention strategies and make objective return-to-participation/sport decisions.

Objective To evaluate the interrater reliability of five different clinically-oriented assessments of hamstring muscle strength.

Design Interrater reliability study.

Setting Sports clubs.

Patients (or Participants) Twenty male field-sport athletes with no reported history of hamstring muscle strain injury within the previous 6 months participated.

Interventions (or Assessment of Risk Factors) Three sports physiotherapists independently assessed participants’ hamstring muscle strength using the following clinically-oriented assessments: (1) supine mid-range maximum voluntary isometric contraction (MVIC); (2) prone inner-range MVIC; (3) prone mid-range MVIC; (4) prone mid-range ‘eccentric break’; (5) supine outer-range ‘eccentric break’.

Main Outcome Measurements Intraclass correlation coefficients (ICCs) and 95% confidence intervals (CI) were calculated to determine interrater reliability. We chose the ICC (2,3) model, which corresponds to a 2-way mixed model, with measurement of the mean of 3 raters and absolute agreement.

Results Excellent interrater reliability was demonstrated for the supine mid-range MVIC (ICC=0.86; 95% CI = 0.70–0.94) and prone mid-range MVIC (ICC=0.79; 95% CI = 0.60–0.91). Good interrater reliability was demonstrated for the prone inner-range MVIC (0.72; 95% CI = 0.44–0.88), prone mid-range ‘eccentric break’ (ICC=0.67; 95% CI = 0.33–0.85), and supine outer-range ‘eccentric break’ (ICC=0.67; 95% CI = 0.34–0.85). The highest and lowest force values were registered during the supine outer-range ‘eccentric break’ (310±57.8N) and prone inner-range MVIC (127±31.4N), respectively.

Conclusions Clinically-oriented assessments of hamstring muscle strength are reliable. These assessments can be used as an integral part of injury prevention, rehabilitation progression and objective return-to- sport decisions.